Traditional multistage charge pumps typically include a network of switched capacitors that boost an input voltage to a higher output voltage, and transfer charge from its input to its output. One important measure of such a charge pump is its power efficiency, which is limited by its output resistance.
Specifically, a high output resistance reduces the power efficiency. Those skilled in the art have responded to this problem by increasing the capacitance of the switched capacitors within the charge pump. Such a solution, however, takes more of the limited chip area that could be available for the circuit. Accordingly, the overall circuit size may increase or have less functionality. Those in the art have also responded to this high output resistance/power efficiency problem by increasing the drive frequency, which undesirably can cause further power loss by driving parasitic capacitance.